"Yours"
as closing

: Two real problem origins for me, can someone help? I'm a librarian in Ohio,
USA in a High School and cannot find an answer to either of these phrases.

:
Played like a fiddle-meaning to be manipulated artfully.

: Yours truly-as in
the sign off of a letter.

: When/where did this begin in our language???

The
Oxford English Dictionary's earliest example of "yours" in the closing of a letter
is dated about 1430. There have been many variations.
"Yours to death, and
after death, Luke Kirbie"
"I depend on your mighty Talent . . . and
on that Score, remain, Most Lovingly Yours."
Presumably the early examples
were written in England.